In today’s constantly changing environment globalization offers opportunities as well as threats to manufacturing companies. One trend in industry is that to meet customer demands and global competition, manufacturing companies need to frequently introduce new products to the market at the right time and cost. Another trend is that manufacturing companies relocate their production sites abroad. Therefore, in this thesis the context is global development projects, which includes both new product development and production relocation projects. The global dimension implies that team members are located in different countries. Integration between team members, which in this thesis refers to interaction processes involving information exchange on the one hand and collaboration or cooperation on the other, is therefore a challenge. Even if much research exists with regard to integration, integration across national borders in global development projects has not been addressed to a greater extent. Therefore, the purpose of this thesis is to expand the analysis of integration in global development projects in order to gain insights regarding the use of different integration mechanisms. The thesis specifically addresses the influence of national cultural and linguistic differences on integration as well as the use of various integration mechanisms. The results originate from one longitudinal case study of a global new product development project and two retrospective case studies including global new product development and production relocation projects. In general, it is concluded that in global development projects national cultural and linguistic differences amplify integration difficulties among project team members who belong to different functions. The comparison of the three global development projects indicated that some of the integration mechanisms worked and were used to integrate team members from different functions, while others did not work as intended. Therefore, this thesis argues that there is a need for a diverse set of integration mechanisms that depend on the context of a global development project and specifically on national cultural and linguistic differences.